Photonics Spectra - March 2009

Expansion seen for UV LED market

LYON, France – Considering the strong potential of the UVA LED business in UV curing, augmented by the growing market demand for UVC LEDs in air and water purification, Yole Développement of Lyon, France, forecasts a cumulated $250 million UV LED market in 2015. Because UVA LEDs are compact, cost-effective and environmentally friendly, they are expected to replace the traditional UV lamp business – a market estimated to be worth $500 million in 2008 – and to make way for new applications, particularly portable ones, according to the market analysis company’s UV LED Market Report – 2009.

UVA LEDs to shine this year and next
Focused on UV LEDs based on GaN
and AlN technologies, the report indicated
that, in 2008, LEDs in the UVA/B spec-
trum (400 to 280 nm) held the largest
share in sub-400-nm applications. It notes
that more than 90 percent of the UV LED
market was allocated to applications that
required UVA/B sources, including UV
curing, banknote counterfeit detection and
medical instrumentation. The remaining
10 percent included a large segment of
UVA-based LED sources (400 to 315 nm)
for photocatalytic air purification.
UV LED light sources definitely can
compete with traditional mercury lamps in
the UV curing business, according to Yole
Développement. Compared with mercury

This air-cooled UV
LED head is available
with focusing lenses for
spot cure of adhesives or inks.
Photo courtesy of Clearstone
Technologies Inc.

lamps, UV LEDs are smaller, nontoxic, more resistant to breakage, have longer lifetime expectations and shorter warm-up times, and easily can be adjusted for system integration.

In the area of heat management, backsided heat extraction is needed with UV LED devices, while traditional UV lamps have homogeneous heat distribution. UVA LEDs’ long lifetimes, lower maintenance costs and power supply cost reductions have contributed to overall lower costs that are competitive with the traditional UV lamp sources. The power output of LEDs has greatly increased, and several watts per square centimeter are expected to be available this year and in 2010. According to the report, many new companies have emerged at the system and LED packaging level.

Today’s UV LED market is oriented mostly toward UVA-emitting diodes because of their similarity to blue GaN diodes, according to Dr. Philippe Roussel, project manager of compound semiconductors and advanced materials at Yole Développement. The major difference in the UVA emitting diodes is a higher aluminum content in the AlGaN compound active layer and specific packaging that is resistant to UV light – enabling applications in UV curing, banknote detectors and photocatalytic air purification, he said. The improvement of UVA LEDs’ performance (lumens per watt and output power)

will enable them to gradually assume market share over the traditional UVA light sources, he added.

UVC LEDs to bloom later

The next booming market is expected to be related to the use of LEDs in the UVC short-wave, or germicidal, range (280 to 100 nm), which will open the door to water- and air-purification applications, according to Roussel. He added that we can expect to see the introduction of commercial air and water disinfectant products by 2010 and 2011 and to see UVC LED applications covering more than 50 percent of the UV LED market by 2013 and 2014. The growth of the UVC LED market is connected strongly to the availability of AlN bulk substrates that theoretically could multiply by 100 the LED chip optical power output, according to Yole Développement. It expects that several companies will provide AlN wafers in volume at the end of 2009. Roussel said that AlN bulk substrates probably are key to achieving highly efficient UVC LEDs. The substrates will improve their emission power greatly, he added.

Portable water purification

Miles Maiden, founder, CEO and chief technology officer of Hydro-Photon Inc. in Blue Hill, Maine, said that his company demonstrated the use of UV LEDs in water purification in 2004 with funding provided by the US Office of Naval Research and with support by DARPA’s Semiconductor Ultraviolet Optical Sources program. Maiden invented the SteriPen, a portable water purifier that uses UV light to destroy waterborne microbes. The company does not have a model that uses UV LED technology, but one is in development. Maiden said that deep-UV LEDs hold promise for even smaller, lighter and faster SteriPen water purifiers, eventually at significantly lower prices.